Testing a Comprehensive Model of the Diffusion of Evidence-Based Practices Science focused on developing evidence-based practices (EBPs) has improved substantially in the past few decades, but the science of ensuring that new treatments and services actually reach patients or populations for whom they are intended has lagged behind. Thus, the proposed study aims to understand factors that promote the delivery of effective services in health care organizations. Four distinct conceptual models now exist to account for variation in the diffusion and implementation of EBPs among health care organizations: (1) a socio- technical model that emphasizes how well the innovation matches the work needs and characteristics of its intended users; (2) an organizational-managerial model that emphasizes technical and social support for the innovation within its host organization; (3) a market model that focuses on the dynamics of local competition and social networks in the diffusion of innovations; and (4) a state regulation model that emphasizes the role of government rules that hinder or support innovation. Yet, few studies have empirically examined the relative importance of these models or how they might combine to influence the diffusion of EBPs. We will examine relationships among these models in a national study of two clinical practices among opioid treatment programs (OTPs): HIV rapid-testing and the prescription of buprenorphine. Since 2006 major changes have occurred in the OTP operating environment and the underlying technology of these practices that could trigger changes in their use of buprenorphine and rates of HIV testing. These changes provide an opportunity to test alternative theories of innovation adoption while also measuring the uptake of important clinical practices. To achieve the proposed study's overall goal, we will meet two specific aims: (1) Assess the extent to which OTPs provide buprenorphine treatment and conduct HIV rapid testing. We will survey a nationally-representative sample of OTPs (n=200) and form a panel data set by linking these data to survey data available from the National Drug Abuse Treatment System Survey (D'Aunno, 2006). (2) Using data from Aim 1, we will empirically examine relationships among the four alternative models of diffusion to identify factors that promote or inhibit the use of EBPs. These factors will be integrated to create a comprehensive conceptual model. Achieving these aims will enable us not only to develop understanding of the diffusion of EBPs in health care organizations, but also to provide information for policy-makers and managers that can increase HIV prevention efforts and access to treatment for millions of regular users of heroin and other opioids. PUBLIC HEALTH RELEVANCE: Our overall goal is to understand factors that promote the diffusion, adoption and implementation of evidence-based practices among health care organizations. We focus particularly on the diffusion and adoption of two clinical practices in the nation's opioid treatment programs: HIV testing and the prescription of buprenorphine Results from the proposed study will enable us not only to develop understanding of the diffusion of evidence-based practices, but also to provide information for policy-makers and managers that can increase HIV prevention efforts and access to treatment for the approximately 1.7 million regular users of heroin and other opioids.